A power factor correction circuit includes a rectifier that rectifies AC power supply voltage, a series circuit of an inductor and a semiconductor switch connected between the rectifier circuit output terminals, and a series circuit of a diode and a smoothing capacitor connected to both ends of the semiconductor switch, a load connected to both ends of the smoothing capacitor, so that the power factor on the input side of the rectifier circuit is corrected by the switching operation of the semiconductor switch. This power factor correction circuit includes a control circuit that controls the switching frequency of the semiconductor switch such that the switching frequency becomes maximum when the ripple of a current flowing through the inductor becomes maximum. According to this power factor correction circuit, normal mode noise can be reduced, and the size of a filter circuit can be decreased.
Legal claims defining the scope of protection. Each claim is shown in both the original legal language and a plain English translation.
1. A power factor correction circuit, comprising: a first series circuit including an inductor and a semiconductor switch for connection between output terminals of an AC power supply, a second series circuit of a diode and a smoothing capacitor connected to both ends of the semiconductor switch, both ends of the smoothing capacitor for connection to a load, a first voltage detection circuit that detects AC power supply voltage as input voltage; and a second voltage detection circuit that detects end-to-end voltage of the smoothing capacitor as output voltage, so that a power factor on an input side of the circuit is corrected by a switching operation of the semiconductor switch, the power factor correction circuit further including a control circuit that controls a switching frequency of the semiconductor switch, wherein the control circuit controls the switching frequency such that the switching frequency becomes a maximum when a ripple of a current flowing through the inductor becomes a maximum, and the control circuit controls the switching frequency to the maximum value by detecting a timing when the ripple becomes the maximum based on a ratio of the input voltage to the output voltage.
This power factor correction circuit connects to an AC power supply and a load. It uses an inductor and semiconductor switch in series, with a parallel circuit of a diode and smoothing capacitor across the switch. The circuit corrects the power factor using the switch. A control circuit adjusts the switch's frequency, maximizing it when the inductor current ripple is highest. The control circuit determines when the ripple is at its maximum by calculating the ratio of the input AC voltage to the output voltage across the smoothing capacitor. It also contains voltage detection circuits for both AC input voltage and output capacitor voltage.
2. The power factor correction circuit according to claim 1 , wherein the control circuit detects that the ripple is the maximum when the ratio of the input voltage to the output voltage is 0.5.
This power factor correction circuit is as described in claim 1. The control circuit in claim 1 determines that the inductor current ripple is at its maximum when the ratio of the input AC voltage to the output voltage across the smoothing capacitor is 0.5. Therefore, the control circuit maximizes the switching frequency of the semiconductor switch when the ratio is 0.5.
3. The power factor correction circuit of claim 1 , further comprising a rectifier circuit for connection between the AC power supply and the first series circuit.
This power factor correction circuit, as described in claim 1, includes a rectifier circuit. The rectifier is placed between the AC power supply and the series circuit containing the inductor and semiconductor switch. The rectifier converts AC voltage from the supply to DC for the rest of the power factor correction circuit. The control circuit adjusts the switch's frequency, maximizing it when the inductor current ripple is highest. The control circuit determines when the ripple is at its maximum by calculating the ratio of the input AC voltage to the output voltage across the smoothing capacitor. It also contains voltage detection circuits for both AC input voltage and output capacitor voltage.
4. A power factor correction circuit, comprising: a first series circuit including an inductor and a semiconductor switch for connection between output terminals of an AC power supply, a second series circuit of a diode and a smoothing capacitor is connected to both ends of the semiconductor switch, both ends of the smoothing capacitor for connection to a load, so that a power factor on an input side of the circuit is corrected by a switching operation of the semiconductor switch, the power factor correction circuit comprising a control circuit that controls a switching frequency of the semiconductor switch variable, wherein the control circuit controls the switching frequency such that the switching frequency becomes a maximum when a third-order harmonic component of a ripple of a current flowing through the inductor becomes a maximum.
This power factor correction circuit connects to an AC power supply and a load. It uses an inductor and semiconductor switch in series, with a parallel circuit of a diode and smoothing capacitor across the switch. The circuit corrects the power factor using the switch. A control circuit adjusts the switch's frequency. The control circuit adjusts the frequency to its maximum value when the third-order harmonic component of the inductor current ripple reaches its maximum.
5. A power factor correction circuit comprising: a first series circuit including an inductor and a semiconductor switch for connection between output terminals of an AC power supply, a second series circuit of a diode and a smoothing capacitor is connected to both ends of the semiconductor switch, both ends of the smoothing capacitor for connection to a load, a first voltage detection circuit that detects AC power supply voltage as input voltage; and a second voltage detection circuit that detects end-to-end voltage of the smoothing capacitor as output voltage, a control circuit that controls a switching frequency of the semiconductor switch variable, so that a power factor on an input side of the circuit is corrected by a switching operation of the semiconductor switch, wherein the control circuit controls the switching frequency to a maximum value by detecting a timing when a third-order harmonic component of the ripple becomes a maximum based on a ratio of the input voltage to the output voltage.
This power factor correction circuit connects to an AC power supply and a load. It uses an inductor and semiconductor switch in series, with a parallel circuit of a diode and a smoothing capacitor across the switch. The circuit corrects the power factor using the switch. The circuit includes voltage detection circuits for both AC input voltage and output capacitor voltage. A control circuit adjusts the switch's frequency. The control circuit adjusts the frequency to its maximum value by detecting when the third-order harmonic component of the inductor current ripple is at its maximum, based on the ratio of the input AC voltage to the output voltage across the smoothing capacitor.
6. The power factor correction circuit according to claim 5 , wherein the control circuit detects that the third-order harmonic component of the ripple is the maximum when the ratio of the input voltage to the output voltage is 5/6, 3/6 or 1/6.
This power factor correction circuit is as described in claim 5. The control circuit in claim 5 determines that the third-order harmonic component of the inductor current ripple is at its maximum when the ratio of the input AC voltage to the output voltage across the smoothing capacitor is 5/6, 3/6, or 1/6. Therefore, the control circuit maximizes the switching frequency of the semiconductor switch when the ratio is 5/6, 3/6 or 1/6.
7. The power factor correction circuit according to claim 5 , wherein the control circuit detects that the third-order harmonic component of the ripple is the maximum when a duty ratio of a pulse to switch the semiconductor switch is 1/6, 3/6 or 5/6.
This power factor correction circuit is as described in claim 5. The control circuit in claim 5 determines that the third-order harmonic component of the inductor current ripple is at its maximum when the duty cycle of the pulse that switches the semiconductor switch is 1/6, 3/6, or 5/6. Therefore, the control circuit maximizes the switching frequency of the semiconductor switch when the duty cycle is 1/6, 3/6 or 5/6.
8. The power factor correction circuit of claim 4 , further comprising a rectifier circuit connected to the first series circuit for connection between the AC power supply and the first series circuit.
This power factor correction circuit, as described in claim 4, includes a rectifier circuit. The rectifier is placed between the AC power supply and the series circuit containing the inductor and semiconductor switch. The rectifier converts AC voltage from the supply to DC for the rest of the power factor correction circuit. The control circuit adjusts the frequency to its maximum value when the third-order harmonic component of the inductor current ripple reaches its maximum.
9. The power factor correction circuit according to claim 3 , further comprising: a first voltage detection circuit that detects AC power supply voltage as input voltage; and a second voltage detection circuit that detects end-to-end voltage of the smoothing capacitor as output voltage, wherein the control circuit controls the switching frequency to a maximum value by detecting a timing when the a third-order harmonic component of the ripple becomes the maximum based on a ratio of the input voltage to the output voltage.
This power factor correction circuit is as described in claim 3. The circuit includes voltage detection circuits for both AC input voltage and output capacitor voltage. The control circuit maximizes the switching frequency of the semiconductor switch by detecting a timing when the third-order harmonic component of the inductor current ripple reaches its maximum, based on a ratio of the input AC voltage to the output voltage.
10. The power factor correction circuit according to claim 9 , wherein the control circuit detects that the third-order harmonic component of the ripple is the maximum when the ratio of the input voltage to the output voltage is 5/6, 3/6 or 1/6.
This power factor correction circuit is as described in claim 9. The control circuit in claim 9 detects that the third-order harmonic component of the inductor current ripple is at its maximum when the ratio of the input AC voltage to the output voltage across the smoothing capacitor is 5/6, 3/6, or 1/6. Therefore, the control circuit maximizes the switching frequency of the semiconductor switch when the ratio is 5/6, 3/6 or 1/6.
11. The power factor correction circuit according to claim 9 , wherein the control circuit detects that the third-order harmonic component of the ripple is the maximum when a duty ratio of a pulse to switch the semiconductor switch is 1/6, 3/6 or 5/6.
This power factor correction circuit is as described in claim 9. The control circuit in claim 9 detects that the third-order harmonic component of the inductor current ripple is at its maximum when the duty cycle of the pulse that switches the semiconductor switch is 1/6, 3/6, or 5/6. Therefore, the control circuit maximizes the switching frequency of the semiconductor switch when the duty cycle is 1/6, 3/6 or 5/6.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
October 13, 2015
October 24, 2017
Browse 5M+ US patents with plain-English claim translations and AI-generated analysis.